Yes, All of the patches in Sp1 are also in SP2. I did this last week for the first time. It worked ok (So Far) I had gone thru the hassle of SP1 then SP2 on previous builds precisely because of the same concerns you are voicing now. One thing I do know for absolute definate is that you can skip SP1a, I have never had it to install anyway!
This thread is now locked and can not be replied to.